Method of Depositing CVD Thin Film

ABSTRACT

It is an object of the present invention to provide a CVD thin film deposition method which can be used for a long time without producing cloggings or the like and can stably supply raw materials to a reaction portion. In the CVD thin film deposition method which forms a predetermined CVD thin film by passing a CVD raw material solution and a gas to a CVD chamber through a vaporizer for an appropriate time, the gas from a vaporizer outlet is switched to an exhaust side and only a solvent which can dissolve attachments adhering to the vaporizer is caused to flow through the vaporizer when the predetermined time passed.

TECHNICAL FIELD

The present invention relates to a method for depositing a CVD thin filmsuch as an MOCVD.

BACKGROUND ART

A problem in development of a DRAM is a storage capacitance involved byrealization of minuteness. Considering software errors or the like, acapacitance that is substantially the same as that in a precedinggeneration is demanded, and hence any measure is required. As such ameasure, a cell structure up to 1 M is a planar structure, but athree-dimensional structure called a stack structure or a trenchstructure is adopted from 4 M in order to increase a capacitor area.Further, as a dielectric film, there has been adopted a film obtained bylaminating a thermal oxide film and a CVD nitride film on poly-Si from athermal oxide film of a substrate Si (this laminated film is generallyreferred to as an ON film). In a 16M DRAM, a three-dimensional typewhich utilizes side surfaces in the stack type, a fin type which alsoutilizes a back side of a plate, or the like has been incorporated inorder to increase an area contributing to a capacity.

In such a three-dimensional structure, however, an increase in thenumber of work stages and an increase in the number of steps due tocomplexity of a process and a reduction in yield due to an increase insteps are regarded as problems, and it is considered that realizationwith 256M bits or above is difficult. Therefore, as one way of furtherincreasing a degree of integration without changing a structure of acurrent DRAM, a method for switching a dielectric of a capacitance tothat having a high dielectric constant has been planed out. Further, asa dielectric film with a high dielectric constant, a thin film of amonometal paraelectric oxide with a high dielectric constant such asTa₂O₅, Y₂O₃, HfO₂ and others has first attracted attention. As to arelative dielectric constant, Ta₂O₅ has 28, Y₂O₃ has 16, and HfO₂ hasapproximately 24, which is four- to seven-fold of that of SiO₂.

However, application to 256M or higher DRAM requires a three-dimensionalcapacitor structure. As materials which have a higher specificdielectric constant than those of the above-described oxides and areexpected to be applied to DRAMs, the following three types areconsidered as strong candidates:

-   -   (Ba_(x)Sr_(1-x))TiO₃;    -   Pb(Zr_(y)Ti_(1-y))O₃; and    -   (Pb_(a)L_(1-a))(Zr_(b)Ti_(1-b))O₃

Further, a Bi-based laminated structure having a crystal structuresimilar to that of a superconductive material has a high dielectricconstant and self-polarization with ferroelectric characteristics and issuperior as a non-volatile memory, and hence it attracts great attentionin recent years.

In general, formation of an SrBi₂TaO₉ ferroelectric thin film is carriedout by an MOCVD (organic metal vapor growth) method that is practicalwith great expectations.

Materials of the ferroelectric thin film are three types of organicmetal complex Sr(DPM)₂, Bi(C₆H₅)₃ and Ta(OC₂H₅)₅, and these materialsare respectively dissolved in THF (tetrahydrofuran), hexane or any othersolvent and used as raw material solutions. Sr(Ta(OE_(t))6)₂ orBi(OtAm)₃ is also solved in hexane or any other solvent, and used as araw material solution. It is to be noted that DPM stands fordipivaloylmethane.

Table 1 shows respective material characteristics. TABLE 1Characteristics of raw materials of the ferroelectric thin film Boilingpoint(° C.)/pressure (mmHg) Fusing point (° C.) Sr(DPM)₂ 231/0.1 210Bi(C₆H₅)₃ 130/0.1 80 Ta(OC₂H₅)₅ 118/0.1 22 THF 67 −109 Sr(Ta(OEt)₆)₂176/0.1 130 Bi(OtAm)₃  87/0.1 90

An apparatus used in the MOCVD method comprises a reaction portion whichcauses a gas phase reaction and a surface reaction of an SrBi₂TaO₉ thinfilm raw material and forms a film, and a supply portion which suppliesthe SrBi₂TaO₉ thin film raw material and an oxidizer to the reactionportion.

Furthermore, the supply portion is provided with a vaporizer whichvaporizes the thin film raw material.

Conventionally, as a technique concerning the vaporizer, each methodshown in FIG. 16 is known. A method shown in FIG. 16(a) is referred toas a metal filter method which performs vaporization by leading a rawmaterial solution heated to a predetermined temperature to a metalfilter which is used to increase a contact area between a gas existingin a surrounding environment and an SrBi₂TaO₉ ferroelectric thin filmraw material solution.

In this technique, however, since the metal filter is clogged due tovaporization for several hours, there is a problem that this techniquecannot withstand a use for a long time. The present inventor hassurmised that this problem occurs since the solutions are heated andvaporization starts from a part with a low vaporization temperature.

FIG. 16(b) shows a technique which discharges a raw material solutionfrom a pore of 10 μm by applying a pressure of 30 kgf/cm² to the rawmaterial solution, and vaporizes the raw material solution byutilization of expansion.

In this technique, however, the pore is clogged due to a use for severalhours, and there is likewise a problem that this technique cannotwithstand a use for a long time.

Moreover, when a raw material solution is a mixed solution using aplurality of organic metal complexes, e.g., a mixed solution ofSr(DPM)₂/THF and Bi(C₆H₅)₃/THF and Ta(OC₂H₅)₅/THF and, when this mixedsolution is vaporized by heating, a solvent with a highest steampressure (THF in this example) is vaporized at first, and there occurs aproblem that the raw material cannot be stably supplied to the reactionportion since each organic metal complex precipitation-adheres to aheated surface. In all of these methods shown in FIG. 1, a heat quantitywhich can cause evaporation or changes of the solution is applied in aliquid or mist state.

Additionally, in the MOCVD, an evaporated gas in which a raw materialsolution is evenly dispersed must be obtained in order to acquire a filmsuperior in evenness. However, the prior art cannot accept this demand.

In order to accept such a demand, the present inventor additionallyprovides the following technique.

That is, as shown in FIG. 15,

there is provided an MOCVD vaporizer comprising:

(1) a dispersion portion having a gas passage formed therein, a gasintroduction opening used to introduce a pressurized carrier gas to thegas passage, means for supplying a raw material solution to the gaspassage, a gas outlet from which the carrier gas including the rawmaterial solution is supplied to a vaporization portion, means forcooling the gas passage, and a radiant heat preventing jet portioncooled in such a manner that a thermal energy is not applied to the rawmaterial gas in the dispersion portion due to radiant heat from thevaporization portion;

(2) a vaporization portion which has a vaporization tube having one endconnected with a reaction tube of an MOCVD apparatus and the other endconnected with the gas outlet, and heating means for heating thevaporization tube, the vaporization portion heating and vaporizing thecarrier gas including the raw material solution supplied from thedispersion portion; and a radiant heat preventing jet portion cooled insuch a manner that a thermal energy is not applied to the raw materialgas in the dispersion portion due to radiant heat from the vaporizationportion.

This technique corresponds to the MOCVD vaporizer which reducescloggings as compared with the prior art, can be used for a long timeand stably apply raw materials to the reaction portion.

Further, according to this technique, an introduction opening ofpreheated oxygen is provided on the downstream side of the vaporizationportion.

However, even if this technique is used, precipitation of a crystal isobserved in the gas passage, and clogging is generated in some cases.

Furthermore, a large quantity of carbon (30 to 40 at %) is contained inthe formed film. In order to remove this carbon, annealing (example:800° C., 60 minutes, oxygen atmosphere) must be carried out at a hightemperature after film formation.

Moreover, when film formation is carried out, a composition ratiobecomes largely uneven.

It is an object of the present invention to provide a method fordepositing a CVD thin film which can be used for a long time withoutgenerating clogging or the like.

DISCLOSURE OF INVENTION

According to the present invention, there is provided a CVD thin filmdeposition method which forms a predetermined CVD thin film by passing aCVD raw material solution and a gas to a CVD chamber for an appropriatetime through a vaporizer, wherein the gas from a vaporizer outlet isswitched to an exhaust side and only a solvent which can dissolveattachments adhering to the vaporizer (which will be referred to as a“cleaning solvent” hereinafter) is caused to flow through the vaporizerwhen the predetermined time passed.

According to the present invention, there is provided a CVD thin filmdeposition method which forms a predetermined CVD thin film by passing aCVD raw material solution and a gas to a CVD chamber for an appropriatetime through a vaporizer, wherein the gas from a vaporizer outlet isswitched to an exhaust side and only a solvent which can dissolveattachments adhering to the vaporizer is caused to flow through thevaporizer to clean the vaporizer when the predetermined time passed, and

an operation of taking out a substrate on which a predetermined thinfilm is formed and setting a new substrate in the CVD chamber isperformed in the CVD chamber simultaneously with the cleaning.

According to the present invention, there is provided a CVD thin filmdeposition method which forms a predetermined CVD thin film by passing aCVD raw material solution and a gas to a CVD chamber for an appropriatetime through a vaporizer,

wherein the gas from a vaporizer outlet is switched to an exhaust sidein order to interrupt deposition of a thin film and a type and a flowquantity of the CVD raw material solution are changed to those of a newCVD raw material solution when the predetermined time passed, and

the new CVD raw material solution and the gas are passed to the CVDchamber through the vaporizer for an appropriate time and deposition ofa thin film is restarted in order to form two types of CVD thin filmshaving different compositions when a sum (capacity) of flow quantitiesof the new CVD raw material solution exceeds onefold or twofold of apipe arrangement capacity from a CVD raw material solution switchingvalve to the vaporizer.

According to the present invention, there is provided a CVD thin filmdeposition method which forms a predetermined CVD thin film by passing aCVD raw material solution and a gas to a CVD chamber for an appropriatetime through a vaporizer,

wherein the CVD thin film deposition method continuously forms two ormore types of CVD thin films by repeating:

a first operation of switching the gas from a vaporizer outlet to anexhaust side in order to interrupt deposition of a thin film andchanging a type and a flow quantity of the CVD raw material solution tothose of a new CVD raw material solution when the predetermined timepassed; and

a second operation of passing the new CVD raw material solution and thegas to the CVD chamber through the vaporizer for an appropriate time andrestarting deposition of a thin film in order to form a second CVD thinfilm having a different composition when a sum (capacity) of flowquantities of the new CVD raw material solution exceeds onefold ortwofold of a pipe arrangement capacity from a CVD raw material solutionswitching valve to the vaporizer.

According to the present invention, there is provided a CVD thin filmdeposition method which forms a predetermined CVD thin film by passing aCVD raw material solution and a gas to a CVD chamber for an appropriatetime through a vaporizer,

wherein the gas from a vaporizer outlet is switched to an exhaust sidein order to interrupt deposition of a thin film, a type and a flowquantity of the CVD raw material solution are changed to those of a newCVD raw material solution and a substrate temperature/reaction pressureis changed when the predetermined time passed, and

two or more types of CVD thin films are continuously formed by repeatinga second operation of passing the new CVD raw material solution and thegas to the CVD chamber through the vaporizer for an appropriate time andrestarting deposition of a thin film in order to form a second CVD thinfilm having a different composition when a sum (capacity) of flowquantities of the new CVD raw material solution exceeds onefold ortwofold of a pipe arrangement capacity from a CVD raw material solutionswitching valve to the vaporizer.

It is preferable that the cleaning solvent is a solvent of a CVD rawmaterial. Cleaning can be effected by just switching a valve withoutpreparing a new cleaning solvent.

It is preferable that the cleaning solvent is one or more of hexane,benzene, toluene, octane and decane. These chemicals can readily preventthe vaporizer in the MOCVD from being clogged.

It is preferable to reduce a pipe arrangement capacity from the CVD rawmaterial switching valve to the vaporizer as much as possible. Forexample, it is preferable to design as shown in FIGS. 26 and 27.

In particular, assuming that (Xcc/min.) means a flow quantity of thecleaning solvent, setting 8 Xcc or below is preferable, setting 2 Xcc orbelow is more preferable, and setting Xcc or below is furtherpreferable. By setting the flow quantity in the above-described range,switching can be very rapidly carried out.

As a vaporizer in the present invention, it is preferable to adopt onecharacterized by comprising:

(1) a dispersion portion having

a gas passage formed therein,

a gas introduction opening from which a carrier gas is introduced to thegas passage,

means for supplying a raw material solution to the gas passage,

a gas outlet from which the carrier gas including the raw materialsolution is supplied to a vaporization portion, and

means for cooling the gas passage; and

(2) a vaporization portion having

a vaporization tube having one end connected to a reaction portion of anapparatus for film formation or of any other type and the other endconnected to the gas outlet, and

heating means for heating the vaporization tube,

the vaporization portion heating the carrier gas which is supplied fromthe dispersion portion and includes the atomized raw material solutionand vaporizing the carrier gas,

the vaporizer having a radiation prevention portion which has a poreprovided on the outer side of the gas outlet.

As a vaporizer in the present invention, it is preferable to adopt onecharacterized by comprising:

(1) a dispersion portion having

a gas passage formed therein,

a gas introduction opening from which a carrier gas is introduced to thegas passage,

means for supplying a raw material solution to the gas passage, and

a gas outlet from which the carrier gas including the raw materialsolution is supplied to a vaporization portion; and

(2) a vaporization portion having

a vaporization tube having one end connected to a reaction portion of anapparatus for film formation or of any other type and the other endconnected to the gas outlet, and

heating means for heating the vaporization tube,

the vaporization portion heating the carrier gas which is supplied fromthe dispersion portion and includes the raw material solution andvaporizing the carrier gas,

(3) the dispersion portion having a dispersion portion main body whichhas a cylindrical or conical hollow portion, and a rod which has anoutside diameter smaller than an inside diameter of the cylindrical orconical hollow portion,

the rod having one or more spiral grooves at the periphery thereof onthe vaporizer side, and being inserted into the cylindrical or conicalhollow portion, the inside diameter of the rod expanding in a taperedform toward the vaporizer side in some cases,

(4) a radiation prevention portion which has a pore on the gas outletside and whose inside diameter expands in a tapered form toward thevaporizer side being provided on the outer side of the gas outlet.

As a vaporizer in the present invention, it is preferable to adopt onecharacterized by comprising:

(1) a dispersion portion having

a gas passage formed therein,

a gas introduction opening from which a carrier gas is introduced to thegas passage,

means for supplying a raw material solution to the gas passage,

a gas outlet from which the carrier gas including the raw materialsolution is supplied to a vaporization portion, and

means for cooling the gas passage; and

(2) a vaporization portion having:

a vaporization tube having one end connected to a reaction portion of anapparatus for film formation or of any other type and the other endconnected to the gas outlet, and

heating means for heating the vaporization tube,

the vaporization portion heating the carrier gas which is supplied fromthe dispersion portion and includes the raw material solution andvaporizing the carrier gas,

the vaporizer being able to add an oxidative gas, such as Ar, N₂, or He,to the carrier gas from the gas introduction opening or introduce theoxidative gas from a primary oxygen supply opening.

As a vaporizer in the present invention, it is preferable to use onecharacterized by comprising:

(1) a dispersion portion having

a gas passage formed therein,

a gas introduction opening from which a carrier gas is introduced to thegas passage,

means for supplying a raw material solution to the gas passage,

a gas outlet from which the carrier gas including the raw materialsolution is supplied to a vaporization portion, and

means for cooling the gas passage; and

(2) a vaporization portion having

a vaporization tube having one end connected to a reaction portion of anapparatus for film formation or of any other type and the other endconnected to the gas outlet, and

heating means for heating the vaporization tube,

the vaporization portion heating the carrier gas which is supplied fromthe dispersion portion and includes the raw material solution andvaporizing the carrier gas,

a radiation prevention portion which has a pore being provided on theouter side of the gas outlet,

the vaporizer being able to introduce the carrier gas and an oxidativegas from the gas introduction opening.

As a vaporization method in the present invention, it is preferable toadopt one characterized in that a vaporization method in the vaporizeris a vaporization method which shears/atomizes the raw material solutionto obtain a raw material mist by introducing the raw material solutionin the gas passage and injecting the carrier gas toward the introducedraw material solution, and then supplies the raw material mist to thevaporization portion in order to vaporize this mist, and this method isa vaporization method which has oxygen contained in the carrier gas.

As a vaporizer in the present invention, it is preferable to adopt onecharacterized by having formed thereto

a plurality of solution passages through which raw material solutionsare supplied,

a mixing portion which mixes the plurality of raw material solutionssupplied from the plurality of solution passages,

a supply passage whose one end communicates with the mixing portion andwhich has an outlet which is on the vaporization side,

a gas passage which is arranged to spray a mixed raw material solutionexiting from the mixing portion with the carrier gas or a mixed gasobtained from the carrier gas and oxygen in the supply passage, and

cooling means for cooling the gas passage.

As a disperser in the vaporizer, it is preferable to adopt onecharacterized by comprising:

a disperser having formed thereto,

a plurality of solution passages through which raw material solutionsare supplied,

a mixing portion which mixes the plurality of raw material solutionssupplied from the plurality of solution passages,

a supply passage whose one end communicates with the mixing portion andwhich has an outlet which is on the vaporization side,

a gas passage which is arranged to spray a mixed raw material solutionexiting from the mixing portion with the carrier gas or a mixed gasobtained from the carrier gas and oxygen in the supply passage, and

cooling means for cooling the gas passage; and

a plurality of solution passages through which raw material solutionsare supplied,

a mixing portion which mixes the plurality of raw material solutionssupplied from the plurality of solution passages,

a supply passage whose one end communicates with the mixing portion andwhich has an outlet which is on the vaporization side,

a gas passage which is arranged to spray a mixed raw material solutionexiting from the mixing portion with the carrier gas or a mixed gasobtained from the carrier gas and oxygen in the supply passage,

cooling means for cooling the gas passage,

a vaporization tube having one end connected to a reaction portion of anapparatus for film formation or of any other type and the other endconnected to an outlet of the disperser, and

heating means for heating the vaporization tube,

the vaporization portion heating the carrier gas which is supplied fromthe dispersion portion and includes the raw material solutions andvaporizing the carrier gas,

a radiation prevention portion which has a pore being provided on theouter side of the gas outlet.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view showing a primary part of an MOCVDvaporizer according to Embodiment 1;

FIG. 2 is an overall cross-sectional view of the MOCVD vaporizeraccording to Embodiment 1;

FIG. 3 is a system chart of an MOCVD;

FIG. 4 is a front view of a reserve tank;

FIG. 5 is a cross-sectional view showing a primary part of an MOCVDvaporizer according to Embodiment 2;

FIG. 6 is a cross-sectional view showing an MOCVD vaporizer according toEmbodiment 3;

FIGS. 7(a) and (b) concern Embodiment 4 and are cross-sectional viewsshowing modifications of a gas passage of the MOCVD vaporizer;

FIG. 8 is a cross-sectional view showing an MOCVD vaporizer according toEmbodiment 5;

FIG. 9 show a rod used in the MOCVD vaporizer according to Embodiment 5,in which (a) is a side view, (b) is an X-X cross-sectional view, and (c)is a Y-Y cross-sectional view;

FIG. 10 is a side view showing a modification of FIG. 9(a);

FIG. 11 is a graph showing an experimental result in Embodiment 6;

FIG. 12 is a side cross-sectional view showing Embodiment 8;

FIG. 13 is a conceptual view showing a gas supply system of Embodiment8;

FIG. 14 is a cross-sectional view showing Embodiment 9;

FIG. 15 is a cross-sectional view showing a latest prior art;

FIGS. 16(a) and (b) are cross-sectional views showing a conventionalMOCVD vaporizer;

FIG. 17 is a graph showing crystallization characteristics of an SBTthin film;

FIG. 18 is a graph showing polarization characteristics of acrystallized SBT thin film;

FIG. 19 is a detail view of the vaporizer;

FIG. 20 is a general view of the vaporizer;

FIG. 21 is a view showing an example of an SBT thin film CVD apparatususing the vaporizer;

FIG. 22 is a cross-sectional view showing a film formation deviceexample;

FIG. 23 is a view showing a structure of heat transfer mediumcirculation used in FIG. 22;

FIG. 24 shows Example 1 of a solution vaporization type CVD apparatuswhich is designed in such a manner that a pipe arrangement capacity froma CVD raw material solution switching valve to a vaporizer becomesminimum;

FIG. 25 shows Example 2 of the solution vaporization type CVD apparatuswhich is designed in such a manner that a pipe arrangement capacity froma CVD raw material solution switching valve to a vaporizer becomesminimum;

FIG. 26 shows a design example of the CVD raw material solutionswitching valve which is designed in such a manner that a pipearrangement capacity becomes minimum; and

FIG. 27 shows a design example of a container valve which is designed insuch a manner that a pipe arrangement capacity becomes minimum.

DESCRIPTION OF REFERENCE NUMERALS

FIG. 2

-   a: FILM FORMATION APPARATUS-   b: COOLING WATER    FIG. 3-   a: RECOVERY SECTION-   b: REACTION SECTION-   c: SUPPLY SECTION-   d: EXHAUST GAS-   e: VAPORIZER-   f: MASS-FLOW CONTROLLER-   g: OXYGEN-   h: HEATED SECTION    FIG. 4-   a: RAW MATERIAL SOLUTION-   b: ARGON    FIG. 7-   a: GAS PASSAGE    FIG. 12-   a: MOCVD APPARATUS-   b: COOLING WATER    FIG. 13-   a: RECOVERY SECTION-   b: REACTION SECTION-   c: SUPPLY SECTION-   d: EXHAUST GAS-   e: VAPORIZER-   f: MASS-FLOW CONTROLLER-   g: OXYGEN-   h: HEATED SECTION    FIG. 16-   a: METAL FILTER    FIG. 19-   a: FIRST CARRIER-   b: RAW MATERIAL SOURCE INTRODUCING ORIFICE-   c: COOLING WATER-   d: SECOND MIXING SECTION & ATOMIZING NOZZLE PORTION-   e: SECOND CARRER-   f: FIRST MIXING SECTION    FIG. 20-   a: SHEATH HEATER-   b: PERMA-   c: HEAT EXCHANGER-   d: VAPORIZATION SECTION PROPER DISTANCE AND TEMPERATURE-   e: MANTLE HEATER-   f: VAPORIZATION HEAD-   g: CONTROLLER-   h: PRESSURE GAGE-   i: VAPORIZATION SECTION AUTOMATIC PRESSURE REGULATING VALVE-   j: THERMOCOUPLE-   k: O₂ OR AIR (SWITCHING OVER)-   l: INTRODUCED GAS (SWIRL MIXING)-   m: HORIZONTAL SECTIONAL VIEW (GAS FLOW IMAGE)-   n: THERMOCOUPLE-   o: SHOWER HEAD-   p: HOT WALL CHAMBER    FIG. 21-   a: DEGASSING SYSTEM-   b: N₂, Ar OR He-   c: HEAT EXCHANGER-   d: SUBSTRATE (4″ TO 8″)-   e: LOAD LOCK CHAMBER-   f: WAFER CONVEYING MECHANISM-   g: LOADER-   h: GATE VALVE-   i: EXHAUST GAS-   j: VAPORIZER-   k: PROCESS CHAMBER    FIG. 24-   a: HEAT EXCHANGER-   b: PROCESS CHAMBER-   c: VAPORIZATION CHAMBER-   d: SUBSTRATE-   e: EXHAUST-   f: LOAD LOCK CHAMBER-   g: LOADER    FIG. 25-   a: HEAT EXCHANGER-   b: PROCESS CHAMBER-   c: VAPORIZATION CHAMBER-   d: SUBSTRATE-   e: EXHAUST-   f: LOAD LOCK CHAMBER-   g: LOADER    FIG. 26-   a: CONTAINER VALVE, BLOCKING-   b: LMFC, BLOCKING-   c: VAPORIZATION HEAD, BLOCKING-   d: CLEANING REPLACING VALVE, BLOCKING-   e: EACH CONTAINER DEAERATION SYSTEM MOUNTED-   f: PRESSURIZATION-   g: PURGE-   h: CLEANING-   i: SOURCE-   j: CONTAINER-   k: VACUUM    FIG. 27-   a: CONVENTIONAL VALVE AND ARRANGEMENT PRESSURIZATION PURGE CLEANING-   b: DEAD SPACE-   c: SOURCE TANK-   d: FORMING ONE BLOCK-   e: AIR OPERATION VALVE-   f: PRESSURIZATION-   g: PURGE-   h: CLEANING-   i: SOURCE-   j: DEAD SPACE MINIMIZATION-   k: FORMING ONE BLOCK-   l: BEST REPLACE ABILITY CAN BE OBTAINED WITH MINIMUM DEAD SPACE BY    PLANETARY-ARRANGING NECESSARY NUMBER OF AIR OPERATION VALVES ON SAME    LEVEL IN ONE BLOCK.-   m: FORMING BLOCK VALVE-   n: MINIMIZING DEAD SPACE

1 dispersion portion main body,

2 gas passage,

3 carrier gas,

4 gas introduction opening,

5 raw material solution,

6 raw material supply hole,

7 gas outlet,

8 dispersion portion,

9 a, 9 b, 9 c, 9 d screw,

10 rod,

18 means for cooling (coolant),

20 vaporization tube,

21 heating means (heater),

22 vaporization portion,

23 connection portion,

24 joint,

25 oxygen introducing means (primary oxygen (oxidative gas) supplyopening,),

26 raw material supply inlet,

30 a, 30 b, 30 c, 30 d massflow controller,

31 a, 31 b, 31 c, 31 d valve,

32 a, 32 b, 32 c, 32 d reserve tank,

33 carrier gas cylinder,

42 exhaust opening,

40 valve,

44 reaction tube,

46 gas pack,

51 taper,

70 groove,

101 pore,

102 radiation prevention portion,

200 oxygen introducing means (secondary oxygen (oxidative gas), carriersupply opening,),

301 upstream ring,

302 downstream ring,

303 a, 303 b heat transfer passage,

304 heat exchange plate,

304 a gas vent gas nozzle,

306 exhaust opening,

308 orifice,

312 substrate heater,

320 heat transfer medium inlet,

321 heat transfer medium outlet,

390 incoming heat transfer medium,

391 outgoing heat transfer medium,

3100 silicon substrate,

BEST MODE FOR CARRYING OUT OF THE INVENTION Embodiment 1

FIG. 1 shows an MOCVD vaporizer according to Embodiment 1.

This example comprises:

a dispersion portion 8 which has:

a gas passage 2 formed in a dispersion portion main body 1 constitutinga dispersion portion, and a gas introduction opening 4 from which apressurized carrier gas 3 is introduced to the gas passage 2,

means (raw material supply hole) 6 for supplying a raw material solution5 to the carrier gas passing through the gas passage 2, and atomizingthe raw material solution 5,

a gas outlet 7 which is used to supply the carrier gas (raw materialgas) including the atomized raw material solution 5 to a vaporizationportion 22,

means (coolant) 18 for cooling the carrier gas flowing through the gaspassage 2; and

a vaporization portion 22 which has:

a vaporization tube 20 having one end connected with a reaction tube ofthe MOCVD apparatus and the other end connected with the gas outlet 7 ofthe dispersion portion 8, and

heating means (heater) 21 for heating the vaporization tube 20, thevaporization portion heating the carrier gas, in which the raw materialsolution is dispersed, supplied from the dispersion portion 8 andvaporizing it,

wherein a radiation prevention portion 102 having a pore 101 is providedon the outer side of the gas outlet 7.

This embodiment will now be described in more detail hereinafter.

In the illustrated example, the inside of the dispersion portion mainbody 1 is a cylindrical hollow portion. A rod 10 is fitted in the hollowportion, and an inner wall of the dispersion main body and the rod 10form the gas passage 2. It is to be noted that the hollow portion is notrestricted to the cylindrical shape, and it may have any other shape.For example, a conical shape is preferable. As an angle of a circularcone of the conical hollow portion, 0 to 45° is preferable, and 8 to 20°is more preferable. This can be likewise applied to any otherembodiment.

It is to be noted that 0.10 to 0.5 mm² is preferable as across-sectional area of the gas passage. If the cross-sectional area isless than 0.10 mm², processing is difficult. If the cross-sectional areaexceeds 0.5 mm², a large flow quantity of the carrier gas having a highpressure must be used in order to increase a speed of the carrier gas.

When a large flow quantity of the carrier gas is used, a large vacuumpump with a large capacity is required in order to maintain a reactionchamber in a pressure reduction state (e.g., 1.0 Torr). Since it isdifficult to adopt a vacuum pump whose exhaust capacity exceeds 10000liter/min. (at, 1.0 Torr), an appropriate flow quantity, i.e., a gaspassage area of 0.10 to 0.5 mm² is preferable in order to achieveindustrial practical applications.

The gas introduction opening 4 is provided at one end of this gaspassage 2. A carrier gas (e.g., N₂, Ar, He) source (not shown) isconnected with the gas introduction opening 4.

The raw material supply opening 6 which communicates with the gaspassage 2 is provided to a substantially central side portion of thedispersion portion main body 1 so that the raw material solution 5 canbe introduced into the gas passage 2 and the raw material solution 5 canbe dispersed in the carrier gas passing through the gas passage 2,thereby obtaining a raw material gas.

The gas outlet 7 communicating with the vaporization tube 20 of thevaporization portion 22 is provided at one end of the gas passage 2.

A space 11 through which a coolant 18 is caused to flow is formed in thedispersion portion main body 1, and the carrier gas flowing through thegas passage 2 is cooled down by passing the coolant 8 through thisspace. Alternatively, for example, a Peltier element or the like may beinstalled in place of this space in order to cool down the gas. Sincethe inside of the gas passage 2 of the dispersion portion 8 is thermallyaffected by the heater 21 of the vaporization portion 22, vaporizationof a solvent alone occurs without generating simultaneous vaporizationof the solvent the raw material and an organic metal complex in the gaspassage 2. Thus, vaporization of the solvent alone is avoided by coolingthe carrier gas which flows through the gas passage 2 and in which theraw material solution is dispersed. In particular, cooling on thedownstream side away from the raw material supply hole 6 is important,and cooling on at least the downstream side of the raw material supplyhole 6 is performed. A cooling temperature is a temperature which is notmore than a boiling point of the solvent. For example, in case of THF, acooling temperature is not more than 67° C. In particular, a temperatureat the gas outlet 7 is important.

In this example, the radiation prevention portion 102 having the pore101 is provided on the outer side of the gas outlet 7. It is to be notedthat reference numerals 103 and 104 denote sealing members such as an Oring. Forming this radiation prevention portion 102 by using, e.g.,Teflon (registered trademark), stainless, ceramics or the like cansuffice. Further, it is preferable to constitute it by using a materialwhich is superior in thermal conductivity.

According to the present inventor's knowledge, heat in the vaporizationportion excessively heats the gas in the gas passage 2 through the gasoutlet 7 as radiant heat in the prior art. Therefore, even if cooling iseffected by using the coolant 18, a low-fusing point component in thegas is separated out in the vicinity of the gas outlet 7.

The radiation prevention portion is a member which prevents such radiantheat from being propagated to the gas. It is, therefore, preferable toset a cross-sectional area of the pore 101 smaller than across-sectional area of the gas passage 2. It is preferable to set it to½ or below, and more preferable to set it to ⅓ or below. Furthermore,reducing a size of the pore is preferable. In particular, it ispreferable to reduce the pore to have a size with which a flow rate ofthe injected gas becomes a subsonic speed.

Moreover, it is preferable for a length of the pore to be fivefold orabove of the size of the pore, and it is more preferable for the same tobe tenfold or above.

Additionally, clogging due to carbides in the gas passage (gas outlet inparticular) is prevented from occurring with respect to a use for a longtime by cooling the dispersion portion.

The dispersion portion main body 1 is connected with the vaporizationtube 20 on the downstream side of the dispersion portion main body 1. Aconnection between the dispersion portion main body 1 and thevaporization tube 20 is achieved by a joint 24, and this portion servesas a connection portion 23.

FIG. 2 shows a general view. The vaporization portion 22 comprises thevaporization tube 20 and the heating means (heater) 21. The heater 21 isa heater which heats and vaporizes the carrier gas which flows throughthe vaporization tube 20 and in which the raw material solution isdispersed. Although the heater 21 is constituted by attaching acylindrical heater or a mantle heater to the outer periphery of thevaporization tube 20 in the prior art, a method which uses a liquid orgas having a large heat capacity as a heat transfer medium is mostexcellent in order to perform heating so as to obtain an eventemperature with respect to a lengthwise direction of the vaporizationtube, and hence this method is adopted.

As the vaporization tube 20, it is preferable to use stainless steel of,e.g., SUS316L. Although it is good enough to appropriately determine asize of the vaporization tube 20 as a length with which a temperature ofthe vaporized gas is sufficiently increased, using a vaporization tubehaving an outside diameter of ¾ inch and a length of several-hundred mmcan suffice when vaporizing, e.g., 0.04 ccm of an SrBi₂Ta₂O₉ rawmaterial solution.

Although a downstream side end of the vaporization tube 20 is connectedwith the reaction tube of the MOCVD apparatus, an oxygen supply opening25 as oxygen supplying means is provided to the vaporization tube 20 inthis example so that oxygen heated to a predetermined temperature can bemixed in the carrier gas.

Supply of the raw material solution to the vaporizer will be firstdescribed.

As shown in FIG. 3, respective reserve tanks 32 a, 32 b, 32 c and 32 dare connected with the raw material supply opening 6 through massflowcontrollers 30 a, 30 b, 30 c and 30 d and valves 31 a, 31 b, 31 c and 31d.

Additionally, a carrier gas cylinder 33 is connected with each of thereserve tanks 32 a, 32 b, 32 c and 32 d.

FIG. 4 shows the detail of the reserve tank.

The raw material solution is filled in the reserve tank, and, forexample, 1.0 to 3.0 kgf/cm² of a carrier gas (e.g., an inert gas Ar, He,Ne) is supplied into each reservoir tank (which has an internal volumeof 300 cc and is made by SUS). Since the inside of the reserve tank ispressurized by the carrier gas, the raw material solution is pushed upin the tube on the side where it is in contact with the solution,supplied to a liquid massflow controller (which is made by STEC and hasa full-scale flow quantity of 0.2 cc/min) by the pressure, a flowquantity is controlled in this controller, and the raw material solutionis transported to the raw material supply hole 6 from a raw materialsupply inlet 29 of the vaporizer.

The raw material solution is transported to the reaction portion by thecarrier gas controlled to have a fixed flow quantity by the massflowcontroller. At the same time, oxygen (oxidizer) controlled to have afixed flow quantity by a massflow controller (which is made by STEC andhas a full-scale flow quantity of 2 L/min) is also transported to thereaction portion.

Since the raw material solution has therein a liquid or solid typeorganic metal complex dissolved in THF as a solvent or any other solventat an ordinary temperature, the organic metal complex is separated outdue to evaporation of the THF solvent and finally enters a solid stateif the raw material solution is left as it stands. It can be, therefore,assumed that tube cloggings or the like are generated in the tubebrought into contact with the undiluted solution. Accordingly, it can beconsidered that cleansing the inside of the tube or of the vaporizerafter a film formation operation by using THF or any other solvent iseffective to suppress cloggings of the tube, and hence a cleansing lineis provided. Cleansing includes a raw material container replacingoperation and is performed in a section from the container outlet sideto the vaporizer, and a portion adapted to each operation is washed awayby using the solvent.

The valves 31 b, 31 c and 31 d are opened, and the carrier gas issupplied into the reserve tanks 32 b, 32 c and 32 d by using thepressure. The raw material solution is supplied to a massflow controller(which is made by STEC and has a full-scale flow quantity of 0.2 cc/min)by the pressure, a flow quantity is controlled in this controller, andthe solution raw material is transported to the raw material supply hole6 of the vaporizer.

On the other hand, the carrier gas is introduced from the gasintroduction opening of the vaporizer. It is preferable to set a maximumpressure on the supply opening side to 3 kgf/cm² or below, a maximumflow quantity which can be passed is approximately 1200 cc/min at thistime, and a passing flow rate in the gas passage 2 reaches a hundred andseveral-ten m/s.

When the raw material solution is introduced from the raw materialsupply hole 6 into the carrier gas flowing through the gas passage 2 inthe vaporizer, the raw material solution is sheared by a high-speed flowof the carrier gas and formed into ultra-fine particles. As a result,the raw material solution is dispersed in the carrier gas in the form ofultra-fine particles. The carrier gas (raw material gas) in which theraw material solution is dispersed in the ultra-fine particle state isatomized and discharged to the vaporization portion 22 while maintaininga high speed. An angle formed by the gas passage and the raw materialsupply hole is optimized. If the carrier flow path and the raw materialsolution introduction opening form a sharp angle (30 degrees), thesolution is pulled by the gas. If the angle is not smaller than 90degrees, the solution is pushed by the gas. An optimum angle isdetermined based on the viscosity/flow quantity of the solution. If theviscosity or the flow quantity is large, making the angle sharper allowsthe solution to smoothly flow. In cases where an SBT film is formed byusing hexane as a solvent, since both the viscosity and the flowquantity are small, an angle of approximately 84 degrees is preferable.

Three types of the raw material solutions controlled to have a fixedflow quantity flow into the gas passage 2 from the raw material supplyhole 6 through the respective raw material supply inlets 29, move in thegas passage together with the carrier gas which has become a high-speedair current, and are then discharged into the vaporization portion 22.In the dispersion portion 8, since the raw material solution is likewiseheated by heat from the vaporization portion 22 and evaporation of thesolvent such as THF is facilitated, a section from the raw materialsupply inlet 29 to the raw material supply hole 6 and a section of thegas passage 2 are cooled by using water or any other cooling medium.

Vaporization of the raw material solution discharged from the dispersionportion 8 in a state that it is dispersed in the carrier gas in the formof fine particles is facilitated while the raw material solution istransported in the vaporization tube 20 heated to a predeterminedtemperature by a heater 21, and the raw material solution becomes amixed gas due to mixing of oxygen heated to a predetermined temperaturewhich is supplied from an oxygen supply opening 25 provided immediatelybefore reaching the reaction tube of the MOCVD and flows into thereaction tube. It is to be noted that evaluation was made by analyzing areaction conformation of the vaporized gas in place of forming a film.

A vacuum pump (not shown) was connected from an exhaust opening 42,impurities such as water contents in the reaction tube 44 were removedby a pressure reduction operation for approximately 20 minutes, and avalve 40 on the downstream side of the exhaust opening 42 was closed.

Approximately 400 cc/min of a coolant of was caused to flow through thevaporizer. On the other hand, 3 kgf/cm² of the carrier gas was caused toflow at 495 cc/min and the reaction tube 44 was sufficiently filled withthe carrier gas. Thereafter, the valve 40 was opened. A temperature atthe gas outlet 7 was lower than 67° C.

The inside of the vaporizer 20 was heated to 200° C., a section from thereaction tube 44 to the gas pack 46 and the gas pack were heated to 100°C., and the inside of the reaction tube 44 was heated to 300° C. to 600°C.

The inside of the reserve tank was pressurized by the carrier gas, and apredetermined liquid was passed by using the massflow controller.

Sr(DPM)₂, Bi(C₆H₅)₃, and Ta(OC₂H₅)₅ and THF were caused to flow based onflow quantities of 0.04 cc/min, 0.08 cc/min, 0.08 cc/min and 0.2 cc/min,respectively.

After 20 minutes, a valve provided immediately before the gas pack 46was opened, a resultant product was recovered into the gas pack 46, itwas analyzed by using a gas chromatograph, and whether the detectedproduct matches with a product in a reaction formula examined based on areactor theory was checked. As a result, in this example, the detectedproduct matched with the product in the reaction formula examined basedon the reactor theory well.

Further, an attachment quantity of a carbide on the outer surface of thedispersion portion main body 1 on the gas outlet 7 side was measured. Asa result, an attachment quantity of the carbide was very small, and itwas much smaller than that obtained by using the apparatus shown in FIG.14.

It is to be noted that if a metal as film raw material is mixed ordissolved in the solvent in order to obtain a raw material solution, itis general that the metal becomes a complex and enters a liquid/liquidstate (complete solvent liquid) in the raw material solution. However,the present inventor has examined the raw material solution in greatdetail and found that the metal complex is not necessarily in a loosemolecular state and the metal complex itself may exist as fine particleshaving a size of 1 to 100 nm in the solvent or it may partially exist ina solid/liquid state. Although it can be considered that clogging invaporization is particularly apt to occur when using the raw materialsolution which is in such a state, using the vaporizer according to thepresent invention does not result in occurrence of clogging even if theraw material solution in such a state is used.

Furthermore, in a stock solution of the raw material solution, fineparticles tend to settle out on a bottom portion due to theirgravitational force. Thus, producing a convection current in the stocksolution by heating the bottom portion (to a temperature which is notmore than an evaporating point of the solvent) and evenly dispersingfine particles are preferable for prevention of clogging. Moreover, itis preferable to heat the bottom portion while cool down the sidesurface of the top face of the container. Of course, heating isperformed at a temperature which is not more than the evaporatingtemperature of the solvent.

Incidentally, it is preferable to set or control the heater in such amanner that a heating calorie in an upper area of the vaporization tubebecomes larger than a heating calories in a downstream area. That is,since the gas subjected to water cooling is emitted from the dispersionportion, it is preferable to provide the heater which sets or controlsto increase a heating calories in the upper area of the vaporizationtube and reduce a heating calorie in the downstream area.

Embodiment 2

FIG. 5 shows an MOCVD vaporizer according to Embodiment 2.

In this example, a coolant passage 106 is formed at the outer peripheryof the radiation prevention portion 102, and cooling means 50 isprovided at the outer periphery of the connection portion 23, therebycooling down the radiation prevention portion 102.

Further, a depression 107 is provided around an outlet of the pore 101.

Any other portion is the same as Embodiment 1.

In this example, it was observed that matching of a detected productwith a product in the reaction formula examined based on the reactortheory is better than that in Embodiment 1.

Furthermore, in regard to a result of measuring an attachment quantityof the carbide on the outer surface of the dispersion portion main body1 on the gas outlet 7 side, the attachment quantity was approximately⅓-fold of that in Embodiment 1.

Embodiment 3

FIG. 6 shows an MOCVD vaporizer according to Embodiment 3.

In this example, a taper 51 is provided to the radiation preventionportion 102. A dead zone at any other portion is eliminated by usingthis taper 51, thereby preventing the raw material from being stored.

Any other point is the same as Embodiment 2.

In this example, it was observed that matching of a detected productwith a product in the reaction formula examined based on the reactortheory is better than that in Embodiment 2.

Moreover, in regard to a result of measuring an attachment quantity of acarbide on the outer surface of the dispersion portion main body 1 onthe gas outlet 7 side, the attachment quantity of the carbide was closeto zero.

Embodiment 4

FIG. 7 shows a modified embodiment of the gas passage.

In FIG. 7(a), grooves 70 are formed on the surface of the rod 10, and anoutside diameter of the rod 10 is substantially the same as an insidediameter of a hole formed in the dispersion portion main body 1.Therefore, the rod 10 can be arranged in the hole without generating theeccentricity by just fitting the rod 10 in the hole. Additionally,screws and the like do not have to be used. This groove 70 serves as agas passage.

It is to be noted that a plurality of grooves 70 may be formed inparallel with a central axis in the longitudinal direction of the rod10, but they may be formed in the spiral form on the surface of the rod10. When the spiral form is adopted, a raw material gas which issuperior in evenness can be obtained.

FIG. 7(b) shows an example in which a mixing portion is provided at anend portion of the rod 10. A maximum diameter at the end portion issubstantially the same as an inside diameter of a hole formed in thedispersion portion main body 1. A space formed by the rod end portionand the inner surface of the hole function as a gas passage.

It is to be noted that the examples shown in (a) and (b) are examples inwhich the surface of the rod 10 is processed, but of course rod having acircular cross-sectional shape may be used as the rod and a concaveportion may be provided to the hole, thereby obtaining a gas passage.

It is preferable to set the rod based on approximately H7×h6 to JS 7which is defined in JIS, for example.

Embodiment 5

Embodiment 5 will now be described with reference to FIG. 8.

An MOCVD vaporizer according to this example comprises:

a dispersion portion 8 having

a gas passage formed therein,

a gas introduction opening 4 from which a pressurized carrier gas 3 isintroduced to the gas passage,

means for supplying raw material solutions 5 a and 5 b to the gaspassage, and

a gas outlet 7 from which the carrier gas including the raw materialsolutions 5 a and 5 b is supplied to a vaporization portion 22; and

a vaporization portion 22 having

a vaporization tube 20 having one end connected to a reaction tube ofthe MOCVD apparatus and the other end connected to the gas outlet 7, and

heating means for heating the vaporization tube 20,

the vaporization portion 22 heating the carrier gas which is suppliedfrom the dispersion portion 8 and includes the raw material solutionsand vaporizing the carrier gas,

the dispersion portion 8 having a dispersion portion main body 1 whichhas a cylindrical hollow portion, and a rod 10 which has an outsidediameter smaller than an inside diameter of the cylindrical hollowportion,

the rod 10 having one or more spiral grooves 60 at the periphery thereofon the vaporizer 22 side,

the rod 10 being inserted into the cylindrical hollow portion,

radiation prevention portion 101 which has a pore 101 and whose insidediameter expands in a tapered form toward the vaporizer 22 side beingprovided on the outer side of the gas outlet 7.

When the raw material solution 5 is supplied to the gas passage throughwhich the carrier gas having a high speed flows, the raw materialsolution is sheared/atomized. That is, the raw material solution as aliquid is sheared and turned into particles by a high-speed current ofthe carrier gas. The raw material solution turned into particles aredispersed in the carrier gas in a particle state. This point is the sameas Embodiment 1.

It is to be noted that the following conditions are preferable in orderto optimally perform shearing/atomization.

It is preferable to supply the raw material solution 5 based on a flowquantity of 0.005 to 2 cc/min, more preferable to supply it based on aflow quantity of 0.005 to 0.02 c/min, and further preferable to supplyit based on a flow quantity of 0.1 to 0.3 cc/min. When a plurality ofraw material solutions (including a solvent) are simultaneouslysupplied, a total quantity of these solutions is used.

Further, it is preferable to supply the carrier gas at a speed of 10 to200 m/sec, and more preferable to supply it at a speed of 100 to 200m/sec.

It is needless to say that a raw material solution flow quantity and acarrier gas flow quantity have a correlation, realize optimumshearing/atomization, and select a flow path cross-sectional area andshape with which ultra-fine particle mists can be obtained.

In this example, since spiral grooves 60 are formed on the periphery ofthe rod 10 and a gap space exists between the dispersion portion mainbody 1 and the rod 10, the carrier gas including the atomized rawmaterial solution moves straight in this gasp space as a straightcurrent and forms a swirling current along the spiral grooves 60.

The present inventor has discovered that the atomized raw materialsolution is evenly dispersed in the carrier gas in a state that both thestraight current and the swirling current exist in this manner. A reasonwhy even dispersion is obtained when both the straight current and theswirling current exist is not necessarily clear, but the following canbe considered. A centrifugal force acts on a flow due to existence ofthe swirling current, and a secondary flow is generated. This secondaryflow facilitates mixing of the raw material and the carrier gas. Thatis, it can be considered that a secondary derived flow is generated in adirection orthogonal to the flow due to the centrifugal effect of theswirling current, and the atomized raw material solution is evenlydispersed in the carrier gas.

This embodiment will now be described in more detail hereinafter.

This embodiment is configured to supply four types of raw materialsolutions 5 a, 5 b, 5 c and 5 d (5 a, 5 b and 5 c are organic metal rawmaterials, and 5 d is a solvent raw material such as THF) into the gaspassage, as an example.

In order to mix the carrier gas including the atomized raw materialsolution in the super-fine particle state (which will be referred to asa “raw material gas”), a part without spiral grooves is provided at adownstream part of a portion of the rod 10 corresponding to the rawmaterial supply hole 6 in this example. This part serves as a pre-mixingportion 65. In the pre-mixing portion 65, the three types of the organicmetal raw material gasses are mixed to some degree, and turned into acomplete mixed raw material gas in an area having a spiral structure onthe downstream side. In order to obtain the even mixed raw material gas,as a length of this mixing portion 65, 5 to 20 mm is preferable, and 8to 15 mm is more preferable. In case of a length out of this range, onlyone of the three types of organic metal raw material gasses, i.e., themixed raw material gas having a high concentration may be possiblysupplied to the vaporization portion 22.

In this example, a parallel portion 67 and a taper portion 58 areprovided to an end portion 66 of the rod 10 on the up stream side. Aparallel portion having the same inside diameter as an outside diameterof the parallel portion 67 of the rod 10 and a taper portion having thesame taper as that of the rod 10, which correspond to the parallelportion 67 and the taper portion 58, are likewise provided to acylindrical hollow portion of the dispersion portion main body 1.Therefore, when the rod 10 is inserted from the upper left side in thedrawing, the rod 10 is held in the hollow portion of the dispersionportion main body 1.

In this example, as different from Embodiment 1, a taper is provided tohold the rod 10, movement of the rod 10 can be prevented even if acarrier gas having a higher pressure than 3 kgf/cm² is used. That is,adopting the holding technique shown in FIG. 8 can cause a carrier gashaving a pressure not less than 3 kg/cm² to flow. As a result, across-sectional area of the gas passage can be reduced, and the carriergas having a higher speed can be supplied with a small quantity of thegas. That is, the carrier gas having a high speed of 50 to 300 mm/s canbe supplied. In the other embodiments mentioned above, the sameadvantages can be obtained by adopting this holding technique.

It is to be noted that grooves 67 a, 67 b, 67 c and 67 d as passages ofthe carrier gas are formed to the part of the rod 10 corresponding tothe raw material supply hole 6 as shown in FIG. 9(b). As a depth of therespective grooves 67 a, 67 b, 67 c and 67, 0.005 to 0.1 mm ispreferable. If the depth is less than 0.005 mm, the groove formingprocessing becomes difficult. Further, 0.01 to 0.05 is more preferable.By setting the depth in this range, clogging or the like is hard to begenerated. Furthermore, a high-speed current can be readily obtained.

As to holding of the rod 10 and formation of the gas passage, thestructure shown in FIG. 1 in Embodiment 1 and any other structures canbe adopted.

As shown in FIG. 9(a), the number of the spiral groove 60 may be one,but a plurality of spiral grooves may be used as shown in FIG. 10.Moreover, the plurality of spiral grooves are formed, they may crosseach other. When the plurality of spiral grooves cross each other, afurther evenly dispersed raw material gas can be obtained. However, itis determined that a cross-sectional area with which a gas flow ratewhich is not more than 10 m/sec can be obtained with respect to eachgroove is used.

The spiral groove 60 is not restricted to specific dimensions/shapes,and the dimension/shape shown in FIG. 9(c) can be taken as an example.

It is to be noted that the gas passage is cooled by using the coolant 18in this example as shown in FIG. 8.

Additionally, in this example, an extended portion 69 is independentlyprovided short of the inlet of the dispersion portion 22, and alongitudinal radiation prevention portion 102 is arranged in thisextended portion.

A pore 101 is formed on the gas outlet 7 side of the radiationprevention portion, and its inside diameter is extended toward thevaporizer side in the tapered form.

This extended portion 69 is also the portion which prevents the rawmaterial gas from being stored, which has been described in conjunctionwith Embodiment 3. Of course, the extended portion 69 does not have tobe independently provided, and it may have an integrated structure asshown in FIG. 6.

As an extension angle θ in the extended portion 69, an angle of 5 to 10degrees is preferable. If θ falls in this range, the raw material gascan be supplied to the dispersion portion without destroying theswirling current. Further, if θ falls in this range, a fluid resistanceobtained by extension becomes minimum, existence of the dead becomesminimum, and existence of eddy currents due to existence of the deadzones can be minimized. It is to be noted that, as θ, an angle of 6 to 7degrees is more preferable. Incidentally, in the case of the embodimentshown in FIG. 6, a preferable range of θ is the same.

Embodiment 6

The raw material solutions and the carrier gas were supplied by usingthe apparatus shown in FIG. 8 under the following conditions, and thehomogeneity in the raw material gas was checked.

Raw material solution introducing quantities:

-   -   Sr(DPM)₂ 0.04 cc/min;    -   Bi(C₆H₅)₃ 0.08 cc/min;    -   Ta(OC₂H₅)₅ 0.08 cc/min; and    -   THF 0.2 cc/min.

Carrier gas: nitrogen gas 10 to 350 m/s

As the vaporizer, the apparatus shown in FIG. 8 was used. As the row,however, there was used a rod having no spiral groove formed to the rodshown in FIG. 9.

The raw material solutions were supplied from the raw material supplyhole 6, and a speed of the carrier gas was changed in many ways. It isto be noted that, from the raw material supply hole 6, Sr(DPM)₂ wassupplied to the groove 67 a, Bi(C₆H₅)₃ was supplied to the groove 67 b,Ta(OC₂H₅)₅ was supplied to the groove 67 c, and a solvent such as THFwas supplied to the groove 67 d.

Heating in the vaporization portion was not carried out, the rawmaterial gas was taken at the gas outlet 7, and a particle size of theraw material solutions in the sampled raw material gas was measured.

FIG. 11 shows a result as a relative value (example using the apparatusaccording to the prior art shown in FIG. 12(a) is determined as 1). Asseen from FIG. 11, a dispersed particle size becomes small when a flowrate is set to 50 m/s or above, and the dispersed particle size becomessmaller by setting the flow rate to 100 m/s or above. However, even ifthe flow rate is set to 200 m/s or above, the dispersed particle size issaturated. Therefore, 100 to 200 m/s is a further preferable range.

Embodiment 7

In this example, a rod having spiral grooves formed thereto was used asthe rod.

Any other structure is the same as Embodiment 6.

In Embodiment 6, a concentration of the raw material solution suppliedto the groove was high in the extended portion of the groove. That is,Sr(DPM)₂ has a high concentration in the extended portion of the groove67 a, Bi(C₆H₅)₃ has a high concentration in the extended portion of thegroove 67 b, and Ta(OC₂H₅)₅ has a high concentration in the extendedportion of the groove 67 c.

In this example, however, in the mixed raw material gas obtained at theend of the spiral groove, each organic metal raw material was uniform inany portion.

Embodiment 8

FIGS. 12 and 13 show Embodiment 8.

Introduction of oxygen was conventionally carried out on the downstreamside alone of the vaporization portion 22 as shown in FIG. 2. A largequantity of carbon is contained in a film formed by the prior art asdescribed in the background art section. Further, there was a differencebetween a composition allocation in the raw material and a compositionallocation in the formed film. That is, when the raw material wasadjusted to have a composition ratio according to the stoichiometry anda film was formed, an actually formed film is a film having acomposition deviating from a stoichiometric ratio. In particular, aphenomenon that almost no bismuth is contained (approximately 0.1 at %)was observed.

The present inventor discovered that this factor relates to an oxygenintroduction position. That is, as shown in FIG. 20, it was found that adifference in composition ratio between a composition in the formed filmand a composition in the raw material solution can be made very small byintroducing oxygen with the carrier gas from the gas introductionopening 4, a secondary oxygen supply opening 200 near a jet and anoxygen introduction opening (primary oxygen supply opening) 25.

It is to be noted that the carrier gas and oxygen may be mixed with eachother in advance and the obtained mixed gas may be introduced from thegas introduction opening 4.

Embodiment 9

An SBT film was formed by using the vaporizer shown in FIGS. 19 and 20and the CVD apparatus shown in FIG. 21, and polarization characteristicsand others were evaluated.

Specifically, conditions of the vaporizer and conditions of a reactionchamber were controlled in the following manner, and an SBT thin filmwas formed on a substrate obtained by forming 200 nm of platinum on anoxidized silicon substrate.

-   Concrete conditions: hexaethoxy strontiumtantalum Sr[Ta(OC₂H₅)₆]₂    0.1 mol solution (solvent: hexane) 0.02 ml/min.;    -   tri-t-amyloxide bismuth Bi(O-t-C₅H₁₁)₃ 0.2 mol solution        (solvent: hexane) 0.02 ml/min.;-   first carrier Ar=200 sccm (introduced from the gas introduction    opening 4);-   first carrier O₂=10 sccm (introduced from the gas introduction    opening 4);-   second carrier Ar=20 sccm (introduced from the gas introduction    opening 200);-   O₂=10 sccm (introduced from the gas introduction opening 200);-   reaction oxygen O₂=200 sccm (introduced from a lower portion 25 of    the dispersion jet portion);-   reaction oxygen temperature 216° C. (temperature is controlled by an    additionally provided heater before introducing from the lower    portion of the dispersion jet portion);-   wafer temperature 475° C.;-   spatial temperature 299° C.;-   spatial distance 30 mm;-   shower head temperature 201° C.;-   reaction pressure 1 Torr; and-   film formation time 20 minutes.    Results-   SBT film thickness approximately 300 nm (deposition speed    approximately 150 nm/min.)-   SBT composition: Sr 5.4 at %;    -   Bi 16.4 at %;    -   Ta 13.1 at %;    -   O 61.4 at %; and    -   C 3.5 at %.

A composition ratio difference between the composition in the formedfilm and the composition in the raw material solution is small, and thedeposition speed is approximately fivefold of that in the prior art. Itcan be understood that the effect of introducing a small quantity ofoxygen with the carrier gas from the gas introduction opening 4 is verylarge. A carbon content is also as small as 3.5 at %.

Since reaction oxygen 200 cc/min was subjected to the accuratetemperature control (216° C.) by using the additionally provided heaterbefore being introduced from the lower portion of the dispersion jetportion, it was confirmed that the effect of suppressingre-condensation/sublimation (solidification) of the vaporized organicmetal compound is large from a fact that contaminations in a lowerportion of the vaporization tube are eliminated.

After formation of this SBT thin film, crystallization processing wasperformed in an oxygen atmosphere at 750° C. for 30 minutes, an upperelectrode was formed and subjected to measurement/evaluation. Itdemonstrated excellent crystallization characteristics and polarizationcharacteristics. These characteristics are shown in FIGS. 17 and 18.

By just introducing an oxidative gas such as oxygen from the gasintroduction opening 4 or the primary oxygen supply opening provided inclose proximity to the jet, introducing oxygen on the downstream side ofthe vaporization portion and appropriately controlling a quantity ofoxygen at the same time are preferable for reducing a composition ratiodifference and decreasing a carbon content.

A content of carbon in the formed film can be reduced to 5% to 20% ofthat in the prior art.

An embodiment of the SBT thin film deposition process will now bedescribed with reference to FIG. 20.

The valve 2 is opened, the valve 1 is closed, a high vacuum is formed inthe reaction chamber, and a wafer is moved to the reaction chamber fromthe load lock chamber after a few minutes.

At this time, in the vaporizer flow the following gases:

-   hexaethoxy strontiumtantalum Sr[Ta(OC₂H₅)₆]₂ 0.1 mol solution    (solvent: hexane) 0.02 ml/min.;-   tri-t-amyloxide bismuth Bi(O-t-C₅H₁₁)₃ 0.2 mol solution (solvent:    hexane) 0.02 ml/min.;-   first carrier Ar=200 sccm (introduced from the gas introduction    opening 4); and-   first carrier O₂=10 sccm (introduced from the gas introduction    opening 4).-   They are led to the vacuum pump through the valve 2 and a pressure    automatic adjustment valve.

At this time, a pressure gauge is controlled to 4 Torr by the pressureautomatic adjustment valve.

After a few minutes from movement of the wafer, when a temperature isstabilized, the valve 1 is opened, the valve 2 is closed, the followinggases are passed to the reaction chamber, and deposition is started.

-   Hexaethoxy strontiumtantalum Sr[Ta(OC₂H₅)₆]₂ 0.1 mol solution    (solvent: hexane) 0.02 ml/min.-   Tri-t-amyloxide bismuth Bi(O-t-C₅H₁₁)₃ 0.2 mol solution (solvent:    hexane) 0.02 ml/min.-   First carrier Ar=200 sccm (introduced from the gas introduction    opening 4)-   First carrier O₂=10 sccm (introduced from the gas introduction    opening 4)-   Second carrier Ar=20 sccm (introduced from the gas introduction    opening 200)-   O₂=10 sccm (introduced from the gas introduction opening 200)-   Reaction oxygen O₂=200 sccm (introduced from a lower portion 25 of    the dispersion jet portion)-   Reaction oxygen temperature 216° C. (temperature is controlled by an    additionally provided heater before introducing from the lower    portion of the dispersion jet portion)-   Wafer temperature 475° C.

A reaction pressure chamber pressure is controlled to 1 Torr (by anon-described pressure automatic adjustment valve).

When a predetermined time (20 minutes in this example) elapses, thevalve 2 is opened, and the valve 1 is closed, thereby terminatingdeposition.

A high vacuum is formed in the reaction chamber to completely remove thereaction gas, and the wafer is taken out to the load lock chamber afterone minute.

Capacitor Structure

Pt (200 nm)/CVDSBT (300 nm)/Pt (175 nm)/Ti (30 nm)/SiO₂/Si

Capacitor Manufacturing Process

Lower electrode forming Pt (175 nm)/TI (30 nm) CVDSBT film formation(300 nm)

SBT film crystallization processing (diffusion furnace annealing: Wafer750° C., 30 min, O₂ atmosphere)

Upper electrode forming Pt (200 nm)

Annealing: 650° C., O₂, 30 min

Since the reaction oxygen (example: 200 sccm) is set in the vaporizationtube in a room temperature state in the prior art, the organic metal gasis cooled and attached to/deposited on the vaporization tube.

When performing a temperature control of the reaction oxygen suppliedfrom the lower portion of the vaporization portion, a heater isconventionally wound around the outside of a stainless tube (outershape: ¼ to 1/16 inch, length: 10 to 100 cm) so that a temperature of anouter wall of the stainless tube can be controlled (e.g., 219° C.).

It was considered that a temperature of the outer wall of the stainlesstube (e.g., 219° C.)=a temperature of oxygen flowing inside (flowquantity 200 sccm).

However, when a temperature of oxygen was measured by using a finethermocouple, the temperature was increased to only approximately 35° C.in the above example.

Thus, an oxygen temperature after heating was directly measured by usinga fine thermocouple, and a heater temperature was controlled, therebyaccurately controlling the oxygen temperature.

Increasing a temperature of a gas such as oxygen flowing through thetube is not easy, a filler was put in the heating tube to improve theheat exchange efficiency, a temperature of the heated oxygen gas wasmeasured, and a temperature of the heater was adequately controlled.

Means for performing this control is a heat exchanger shown in FIG. 20.

Embodiment 10

FIG. 14 shows Embodiment 10.

Although the foregoing embodiment atomizes each single raw materialsolution by spraying with a gas and then mixes the atomized raw materialsolutions, this example is an apparatus which mixes a plurality of rawmaterial solutions and then atomizes the mixed raw material solution.

This example has:

a disperser 150 having formed therein a plurality of solution passages130 a and 130 b through which raw material solutions 5 a and 5 b aresupplied, a mixing portion 109 which mixes the plurality of raw materialsolutions 5 a and 5 b supplied from the plurality of solution passages130 a and 130 b, a supply passage 110 whose one end communicates withthe mixing portion 109 and which has an outlet 017 which is on avaporization portion 22 side, a gas passage 120 which is arranged tospray the mixed raw material solution fed from the mixing portion 109with a carrier gas or a mixed gas of the carrier gas and oxygen, andcooling means for cooling the inside of the supply passage 110; and

a vaporization portion 22 which has a vaporization tube having one endconnected with a reaction tube of an MOCVD apparatus and the other endconnected with the outlet 107 of the disperser 150, and heating means 2for heating the vaporization tube, the vaporization portion 22 heatingand vaporizing the gas including the raw material solutions,

wherein a radiant heat prevention material 102 having a pore 101 isarranged on the outer side of the outlet 107.

This example is effective for the raw material solutions which are slowto react even if mixed and, since such solutions are atomized aftermixing, a composition becomes accurate as compared with an example inwhich mixing is performed after atomization. Further, a more accuratecomposition can be obtained by providing means (not shown) for analyzinga composition of the mixed raw material solution in the mixing portion109 and controlling supply quantities of the raw material solutions 5 aand 5 b based on an analysis result.

Furthermore, in this example, since a rod (10 in FIG. 1) does not haveto be used, heat propagated through the rod does not heat the inside ofthe supply passage 110. Moreover, since a cross-sectional area of thesupply passage 110 can be reduced and a cross-sectional area of theoutlet 107 can be also decreased as compared with an example in whichmixing is performed after atomization, the inside of the supply passage110 is rarely heated by radiation. Therefore, precipitation or the likeof a crystal can be reduced without providing the radiation preventionportion 102. However, when precipitation of a crystal should be furtherprevented, the radiation prevention portion 102 may be provided as shownin FIG. 14.

It is to be noted that the above embodiment shows the example in whichthe number of the pore is one, but a plurality of such pores may beprovided. Moreover, as a diameter of the pore, 2 mm or below ispreferable. If the plurality of pores are provided, a smaller diametercan be adopted.

Additionally, in the above-described embodiment, if the carrier flowpath and the raw material solution introduction opening form a sharpangle (30 degrees), the solution is pulled by the gas. If this angle isnot less than 90 degrees, the solution is pushed by the gas. Therefore,an angle of 30 to 90 degrees is preferable. Specifically, an optimumangle is determined based on the viscosity/flow quantity of thesolution. If the viscosity is large or the flow quantity is large,making a sharp angle allows the solution to smoothly flow. Therefore,when embodying the present invention, it is good enough to obtain anoptimum angle according to the viscosity/flow quantity from anexperiment or the like.

Additionally, in the above-described embodiment, it is preferable toprovide a mechanism which controls a distance of a space between ashower head and a susceptor to an arbitrary distance.

Further, it is preferable to provide a liquid massflow controller whichcontrols a flow quantity of the raw material solution and deaeratingmeans for deaeration on the upstream side of the liquid massflowcontroller. When the raw material solution is introduced to the massflowcontroller without performing deaeration, irregularities of a formedfilm is generated on the same wafer or between wafers. By introducingthe raw material solution to the massflow controller after deaerating,e.g., helium, the irregularities in the film thickness are considerablyreduced.

Provision of means for controlling temperatures of the raw materialsolution, a helium thrusting container, the liquid massflow containerand pipes in the vicinity of these members to fixed temperatures canfurther prevent irregularities in film thickness. Furthermore, it ispossible to avoid a degeneration change in quality of the raw materialsolution which is chemically unstable. When forming the SBT thin film, aclose control is performed in a range of 5° C. to 20° C. In particular,a range of 12° C.±1° C. is desirable.

Moreover, as a substrate surface finishing apparatus which sprays asurface of a substrate, e.g., a silicon substrate such as shown in FIGS.22 and 23 with a predetermined gas and performs surface finishing on thesubstrate surface, it is preferable to use an apparatus which has anupstream ring 301 connected with a heat transfer medium inlet 320through which a heat transfer medium flows, a downstream ring 302connected with a heat transfer medium outlet 321 for the predeterminedheat transfer medium, and at least two heat transfer passages 303 a and303 b which are connected between the upstream ring 1 and the downstreamring 2 in parallel with each other and form a flow path of the heattransfer medium, wherein directions of flow paths from the upstream ring1 to the downstream ring 302 between the adjacent heat transfer passages303 a and 303 b are alternate and a heat transfer circulation path whichobtains a predetermined temperature of the gas is constituted.

Moreover, it is preferable for the substrate surface finishing apparatusto have a thermal conversion plate 304 which is thermally connected withthe heat transfer medium circulation path in a plane on which the flowpath of the heat transfer medium is formed in the parallel directionwhich is a predetermined plane in the heat transfer medium circulationpath, so that the plane of the thermal conversion plate 304 can beheated to a substantially even temperature by using the heat transfermedium.

Additionally, a plurality of air holes through which the predeterminedgas is passed in a direction vertical to the plane are formed on theplane of the thermal conversion plate 304 so that the predetermined gaspassing through the air holes can be heated to a substantially eventemperature in the plane.

As a result, the directions of the flow paths from the upstream ring tothe downstream ring between the adjacent heat transfer passages of theheat transfer medium circulation path are constituted to be alternate.Therefore, temperature differences of areas adjacent to the heattransfer passages are configured to be high/low/high/low . . . . Withthis structure, the thermal conversion plate can be evenly heated orcooled. Further, a thermal conversion plate thermally connected with theheat transfer medium circulation path is provided in the plane on whichthe flow path of the heat transfer medium is formed in the paralleldirection. Therefore, the plane of this thermal conversion plate can befurther heated to a substantially even temperature.

Embodiment 11

An improvement example of the SBT thin film deposition process will nowbe described with reference to FIG. 24.

A valve 206V2 is opened, a valve 208V1 is closed, a reaction chamber(process chamber) is caused to form a high vacuum, and a wafer is movedinto the reaction chamber 203 from a load lock chamber 204 after oneminute.

At this time, the following materials flow through a vaporizer(vaporization chamber) 205.

-   Hexaethoxy strontiumtantalum Sr[Ta(OC₂H₅)₆]₂ 0.004 mol solution    (solvent: hexane) 0.50 ml/min.-   Tri-t-amyloxide bismuth Bi(O-t-C₅H₁₁)₃ 0.008 mol solution (solvent:    hexane) 0.50 ml/min.-   First carrier Ar=200 sccm (introduced from the gas introduction    opening 4)-   First carrier O₂=10 sccm (introduced from the gas introduction    opening 4)

The raw materials are exhausted to a vacuum pump through the valve 206V2and a pressure automatic adjustment valve 207.

At this time, a pressure gauge is controlled to 4 Torr by the pressureautomatic adjustment valve.

When the wafer is moved and a temperature is stabilized after fourminutes, the valve 208V1 is opened, the valve 206V2 is closed, thefollowing gases are passed to the reaction chamber 203, thereby startingdeposition. Hexaethoxy strontiumtantalum Sr[Ta(OC₂H₅)₆]₂ 0.004 molsolution (solvent: hexane) 0.50 ml/min.

-   Tri-t-amyloxide bismuth Bi(O-t-C₅H₁₁)₃ 0.2 mol solution (solvent:    hexane) 0.50 ml/min.-   First carrier Ar=200 sccm (introduced from the gas introduction    opening 4)-   First carrier O₂=10 sccm (introduced from the gas introduction    opening 4)-   Second carrier Ar=20 sccm (introduced from the gas introduction    opening 200)-   O₂=10 sccm (introduced from the gas introduction opening 200)-   Reaction oxygen O₂=200 sccm (introduced from a lower portion 25 of    the dispersion jet portion)-   Reaction oxygen temperature 216° C. (temperature is controlled by an    additionally provided heater before introducing from the lower    portion of the dispersion jet portion)-   Wafer temperature 475° C.-   A pressure in the reaction pressure chamber is controlled to 1 Torr    (by a non-illustrated pressure automatic adjustment valve).

When a predetermined time (e.g., 20 minutes in this example) elapses,the valve 206V2 is opened, and the valve 208V1 is closed, therebyterminating deposition.

An SBT thin film having a thickness of approximately 200 nm wasdeposited.

A high vacuum is formed in the reaction chamber 203 to completely removethe reaction gas, and the wafer is taken out to the load lock chamber204 after one minute. Then, a new wafer is set, and the valve 206V isclosed whilst the valve 208V1 is opened after four minutes, therebystarting deposition.

Although there is a time of approximately five minutes after terminationof deposition and before start of deposition of the next wafer, cleaningof the vaporizer 205 is carried out in this period. High-purity hexaneis passed to MAC of a 0.004 mol solution (solvent: hexane) of hexaethoxystrontiumtantalum Sr[Ta(OC₂H₅)₆]₂ and a 0.008 mol solution (solvent:hexane) of tri-t-amyloxide bismuth Bi(O-t-C₅H₁₁)₃ immediately aftertermination of deposition.

A total flow quantity is 1.0/min, and a time is three minutes.

When three minutes elapses, the raw materials are switched to a 0.004mol solution (solvent: hexane) of hexaethoxy strontiumtantalumSr[Ta(OC₂H₅)₆]₂ and a 0.008 mol solution (solvent: hexane) oftri-t-amyloxide bismuth Bi(O-t-C₅H₁₁)₃.

After two minutes from switching, deposition of the SBT thin film isagain started.

Since a pipe arrangement capacity is 1.2 cc, cleaning of the vaporizerwas performed by the above-described operation. When the vaporizer wasdisassembled and inspected after repeating this operation for 20 times,the vaporizer, especially an atomization nozzle portion has nocontamination.

Embodiment 12

An improvement example of the SBT thin film deposition process will nowbe described with reference to FIG. 25.

The valve 206V2 is opened, the valve 208V1 is closed, a high vacuum isformed in the reaction chamber 203, and a wafer is moved into thereaction chamber 203 from the load lock chamber 204 after one minute.

At this time, the following raw materials flow through the vaporizer.

-   Hexaethoxy strontiumtantalum Sr[Ta(OC₂H₅)₆]₂ 0.004 mol solution    (solvent: hexane) 0.50 ml/min.-   Tri-t-amyloxide bismuth Bi(O-t-C₅H₁₁)₃ 0.008 mol solution (solvent:    hexane) 0.60 ml/min.-   First carrier Ar=200 sccm (introduced from the gas introduction    opening 4)-   First carrier O₂=10 sccm (introduced from the gas introduction    opening 4)-   They are drawn toward the vacuum pump through the valve 206V2 and    the pressure automatic adjustment valve 207.

At this time, the pressure gauge is controlled to 4 Torr by the pressureautomatic adjustment valve. The wafer is moved and a temperature isstabilized after four minutes, the valve 208V1 is opened, the valve206V2 is closed, and the following gases are passed to the reactionchamber 203 to start deposition.

-   Hexaethoxy strontiumtantalum Sr[Ta(OC₂H₅)₆]₂ 0.004 mol solution    (solvent: hexane) 0.50 ml/min.-   Tri-t-amyloxide bismuth Bi(O-t-C₅H₁₁)₃ 0.2 mol solution (solvent:    hexane) 0.60 ml/min.-   First carrier Ar=200 sccm (introduced from the gas introduction    opening 4)-   First carrier O₂=10 sccm (introduced from the gas introduction    opening 4)-   Second carrier Ar=20 sccm (introduced from the gas introduction    opening 200)-   O₂=10 sccm (introduced from the gas introduction opening 200)-   Reaction oxygen O₂=200 sccm (introduced from a lower portion 25 of    the dispersion jet portion),-   Reaction oxygen temperature 216° C. (temperature is controlled by an    additionally provided heater before introducing from the lower    portion of the dispersion jet portion)-   Wafer temperature 475° C.-   A pressure in the reaction pressure chamber is controlled to 1 Torr    (by a non-illustrated pressure automatic adjustment valve).

When one minute elapses, the valve 206V2 is opened and the valve 208V1is closed, thereby terminating deposition.

Flow quantities are then changed.

-   Hexaethoxy strontiumtantalum Sr[Ta(OC₂H₅)₆]₂ 0.004 mol solution    (solvent: hexane) 0.50 ml/min.-   Tri-t-amyloxide bismuth Bi(O-t-C₅H₁₁)₃ 0.2 mol solution (solvent:    hexane) 0.50 ml/min.

After one minute, the valve 208V1 is opened and the valve 206V2 isclosed in order to restart deposition. After seven minutes elapse, thevalve 206V2 is opened and the valve 208V1 is closed, thereby terminatingdeposition.

An SBT thin film having a thickness of approximately 80 nm wasdeposited.

A high vacuum is formed in the reaction chamber 203 to completely removethe reaction gas, and the wafer is taken out to the load lock chamber205 after one minute. A new wafer is then set, and the valve 206V2 isclosed whilst the valve 208V1 is opened after four minutes, therebystarting deposition.

INDUSTRIAL APPLICABILITY

-   1. Although droplets adhere to an end of the vaporizer and a    five-hour operation causes clogging in the prior art, the present    invention can provide a vaporizer for a film formation apparatus for    MOCVD or the like or any other apparatus which can be used for a    long time without producing clogging and stably supply raw materials    to a reaction portion.-   2. A composition of a CVD thin film can be changed/controlled in a    thickness direction.-   3. A reduction in cost can be achieved.-   4. A reduction in deposition speed and deposition rate can be    eliminated.

1. A CVD thin film deposition method which forms a predetermined CVDthin film by passing a CVD raw material solution and a gas to a CVDchamber for an appropriate time through a vaporizer, wherein the gasfrom a vaporizer outlet is switched to an exhaust side and only asolvent which can dissolve attachments adhering to the vaporizer (whichwill be referred to as a “cleaning solvent” hereinafter) is caused toflow through the vaporizer when the predetermined time passed.
 2. TheCVD thin film deposition method according to claim 1, wherein thecleaning solvent is a solvent of a CVD raw material.
 3. The CVD thinfilm deposition method according to claim 1, wherein the cleaningsolvent is one or more of hexane, benzene, toluene, octane and decane.4. The CVD thin film deposition method according to any of claims 1 to3, wherein a pipe arrangement capacity from a CVD raw material solutionswitching valve to the vaporizer is not more than 8 Xcc when a flowquantity of the cleaning solvent is determined as (Xcc/min.).
 5. The CVDthin film deposition method according to any of claims 1 to 3, wherein apipe arrangement capacity from the CVD raw material solution switchingvalve to the vaporizer is not more than 2 Xcc when a flow quantity ofthe cleaning solvent is determined as (Xcc/min.).
 6. The CVD thin filmdeposition method according to any of claims 1 to 3, wherein a pipearrangement capacity from the CVD raw material solution switching valveto the vaporizer is not more than Xcc when a flow quantity of thecleaning solvent is determined as (Xcc/min.).
 7. A CVD thin filmdeposition method which forms a predetermined CVD thin film by passing aCVD raw material solution and a gas to a CVD chamber for an appropriatetime through a vaporizer, wherein the gas from a vaporizer outlet isswitched to an exhaust side and only a solvent which can dissolveattachments adhering to the vaporizer is caused to flow through thevaporizer to clean the vaporizer when the predetermined time passed, andan operation of taking out a substrate on which a predetermined thinfilm is formed and setting a new substrate in the CVD chamber isperformed in the CVD chamber simultaneously with the cleaning.
 8. A CVDthin film deposition method which forms a predetermined CVD thin film bypassing a CVD raw material solution and a gas to a CVD chamber for anappropriate time through a vaporizer, wherein the gas from a vaporizeroutlet is switched to an exhaust side in order to interrupt depositionof a thin film and a type and a flow quantity of the CVD raw materialsolution are changed to those of a new CVD raw material solution whenthe predetermined time passed, and the new CVD raw material solution andthe gas are passed to the CVD chamber through the vaporizer for anappropriate time and deposition of a thin film is restarted in order toform two types of CVD thin films having different compositions when asum (capacity) of flow quantities of the new CVD raw material solutionexceeds onefold or twofold of a pipe arrangement capacity from a CVD rawmaterial solution switching valve to the vaporizer.
 9. A CVD thin filmdeposition method which forms a predetermined CVD thin film by passing aCVD raw material solution and a gas to a CVD chamber for an appropriatetime through a vaporizer, wherein the CVD thin film deposition methodcontinuously forms two or more types of CVD thin films by repeating: afirst operation of switching the gas from a vaporizer outlet to anexhaust side in order to interrupt deposition of a thin film andchanging a type and a flow quantity of the CVD raw material solution tothose of a new CVD raw material solution when the predetermined timepassed; and a second operation of passing the new CVD raw materialsolution and the gas to the CVD chamber through the vaporizer for anappropriate time and restarting deposition of a thin film in order toform a second CVD thin film having a different composition when a sum(capacity) of flow quantities of the new CVD raw material solutionexceeds onefold or twofold of a pipe arrangement capacity from a CVD rawmaterial solution switching valve to the vaporizer.
 10. A CVD thin filmdeposition method which forms a predetermined CVD thin film by passing aCVD raw material solution and a gas to a CVD chamber for an appropriatetime through a vaporizer, wherein the gas from a vaporizer outlet isswitched to an exhaust side in order to interrupt deposition of a thinfilm, a type and a flow quantity of the CVD raw material solution arechanged to those of a new CVD raw material solution and a substratetemperature/reaction pressure is changed when the predetermined timepassed, and two or more types of CVD thin films are continuously formedby repeating a second operation of passing the new CVD raw materialsolution and the gas to the CVD chamber through the vaporizer for anappropriate time and restarting deposition of a thin film in order toform a second CVD thin film having a different composition when a sum(capacity) of flow quantities of the new CVD raw material solutionexceeds onefold or twofold of a pipe arrangement capacity from a CVD rawmaterial solution switching valve to the vaporizer.
 11. The CVD thinfilm deposition method according to any of claims 1-3 and 7-10, whereinthe vaporizer comprises: (1) a dispersion portion having a gas passageformed therein, a gas introduction opening from which a carrier gas isintroduced to the gas passage, means for supplying a raw materialsolution to the gas passage, a gas outlet from which the carrier gasincluding the raw material solution is supplied to a vaporizationportion, and means for cooling the gas passage; and (2) a vaporizationportion having a vaporization tube having one end connected to areaction portion of an apparatus for film formation or of any other typeand the other end connected to the gas outlet, and heating means forheating the vaporization tube, the vaporization portion heating thecarrier gas which is supplied from the dispersion portion and includesthe atomized raw material solution and vaporizing the carrier gas, thevaporizer having a radiation prevention portion which has a poreprovided on the outer side of the gas outlet.
 12. The CVD thin filmdeposition method according to any of claims 1-3 and 7-10, wherein thevaporizer comprises: (1) a dispersion portion having a gas passageformed therein, a gas introduction opening from which a carrier gas isintroduced to the gas passage, means for supplying a raw materialsolution to the gas passage, and a gas outlet from which the carrier gasincluding the raw material solution is supplied to a vaporizationportion; and (2) a vaporization portion having a vaporization tubehaving one end connected to a reaction portion of an apparatus for filmformation or of any other type and the other end connected to the gasoutlet, and heating means for heating the vaporization tube, thevaporization portion heating the carrier gas which is supplied from thedispersion portion and includes the raw material solution and vaporizingthe carrier gas, (3) the dispersion portion having a dispersion portionmain body which has a cylindrical or conical hollow portion, and a rodwhich has an outside diameter smaller than an inside diameter of thecylindrical or conical hollow portion, the rod having one or more spiralgrooves at the periphery thereof on the vaporizer side, and beinginserted into the cylindrical or conical hollow portion, the insidediameter of the rod expanding in a tapered form toward the vaporizerside in some cases, (4) a radiation prevention portion which has a poreon the gas outlet side and whose inside diameter expands in a taperedform toward the vaporizer side being provided on the outer side of thegas outlet.
 13. The CVD thin film deposition method according to any ofclaims 1-3 and 7-10, wherein the vaporizer comprises: (1) a dispersionportion having a gas passage formed therein, a gas introduction openingfrom which a carrier gas is introduced to the gas passage, means forsupplying a raw material solution to the gas passage, a gas outlet fromwhich the carrier gas including the raw material solution is supplied toa vaporization portion, and means for cooling the gas passage; and (2) avaporization portion having: a vaporization tube having one endconnected to a reaction portion of an apparatus for film formation or ofany other type and the other end connected to the gas outlet, andheating means for heating the vaporization tube, the vaporizationportion heating the carrier gas which is supplied from the dispersionportion and includes the raw material solution and vaporizing thecarrier gas, the vaporizer being able to add an oxidative gas to thecarrier gas from the gas introduction opening or introduce the oxidativegas from a primary oxygen supply opening.
 14. The CVD thin filmdeposition method according to any of claims 1-3 and 7-10, wherein thevaporizer comprises: (1) a dispersion portion having a gas passageformed therein, a gas introduction opening from which a carrier gas isintroduced to the gas passage, means for supplying a raw materialsolution to the gas passage, a gas outlet from which the carrier gasincluding the raw material solution is supplied to a vaporizationportion, and means for cooling the gas passage; and (2) a vaporizationportion having a vaporization tube having one end connected to areaction portion of an apparatus for film formation or of any other typeand the other end connected to the gas outlet, and heating means forheating the vaporization tube, the vaporization portion heating thecarrier gas which is supplied from the dispersion portion and includesthe raw material solution and vaporizing the carrier gas, a radiationprevention portion which has a pore being provided on the outer side ofthe gas outlet, the vaporizer being able to introduce the carrier gasand an oxidative gas from the gas introduction opening.
 15. The CVD thinfilm deposition method according to any of claims 1-3 and 7-10, whereinthe vaporizer comprises: a disperser having formed thereto, a pluralityof solution passages through which raw material solutions are supplied,a mixing portion which mixes the plurality of raw material solutionssupplied from the plurality of solution passages, a supply passage whoseone end communicates with the mixing portion and which has an outletwhich is on the vaporization side, a gas passage which is arranged tospray a mixed raw material solution exiting from the mixing portion withthe carrier gas or a mixed gas obtained from the carrier gas and oxygenin the supply passage, and cooling means for cooling the gas passage;and a vaporization portion having a vaporization tube having one endconnected to a reaction portion of an apparatus for film formation or ofany other type and the other end connected to an outlet of thedisperser, and heating means for heating the vaporization tube, thevaporization portion heating the carrier gas which is supplied from thedispersion portion and includes the raw material solutions andvaporizing the carrier gas, a radiation prevention portion which has apore being provided on the outer side of the gas outlet, a primaryoxygen supply opening from which an oxidative gas can be introducedbeing provided in close proximity to the dispersion jet portion.
 16. TheCVD thin film deposition method according to any of claims 1-3 and 7-10,wherein a vaporization method in the vaporizer is a vaporization methodwhich shears/atomizes the raw material solution to obtain a raw materialmist by introducing the raw material solution in the gas passage andinjecting the carrier gas toward the introduced raw material solution,and then supplies the raw material mist to the vaporization portion inorder to vaporize this mist, and this method is a vaporization methodwhich has oxygen contained in the carrier gas.